This invention is directed toward knife sharpeners, and more particularly, toward an improved sharpening blade configuration for forming a sharper cutting edge on a knife or the like.
Many knife sharpeners have been developed over the years that are directed toward new and improved methods for sharpening a knife edge. The numerous sharpeners include different configurations for blade shapes, blades having a plurality of sharpening edges wherein the blades are adapted to be moved or the like for exposing new edges, and supports and combined tools directed toward more conveniently placing the sharpening blades in position for use. The blade configurations include circular cutting blades, triangular cutting blades and square or rectangular cutting blades. Supports and the like include those which can be permanently attached to a work bench or the like, those which can be hand held and others which are self-supportive. In addition, tools have been invented which combine a knife sharpener with another tool such as a file or screwdriver.
U.S. Pat. No. 469,615 to Wardwell discloses a knife sharpener having abutting circular blades lying in the same vertical plane. The knife sharpener includes a support base which is adapted to attach to a permanent structure. While the Wardwell sharpener would seem to apply a circular and narrow configuration to the edge being sharpened, because of the large radius inherent in circular disks, the lead-in groove is relatively large, forming only a broad based edge having a sharp point.
U.S. Pat. No. 584,933 to Friedrich discloses a sharpener having square and rotatably attached overlapping sharpening blades also having bevelled edges. The blades in the Friedrich sharpener overlap, using the overlapping configuration to apply pressure to the knife edge being passed through the blades. The blades are rotatably attached and have a plurality of sharpening edges thereon so that the blades can be rotated to expose a fresh sharpening edge when others become dull. The sharpener in Friedrich, however, does not have rounded intersections or corners or the like which give to the knife edge, a rounded and more streamlined configuration. Additionally, the Friedrich blades, being of the overlapping nature, are in conflict with the general principles of this invention.
The patent to Keezer et al., U.S. Pat. No. 1,622,197, discloses a knife sharpener having a support and base for attachment to a permanent structure. The blades therein are elongated and triangularly shaped and are arranged to be mutually engaging. However, unlike the instant invention, the corners of the blades are not rounded and the blades engage and intersect at a point, having no lead-in radius. Therefore, again no streamlined edge is produced on the knife through sharpening the same.
In addition to the above, the patents to Jones, U.S. Pat. No. 2,436,810; Pleasants, U.S. Pat. No. 3,289,498; and Judd et al., U.S. Pat. No. 1,474,636 disclose additional knife sharpeners having circularly-shaped blades which also exhibit the same shortcomings as those patents discussed above. U.S. Pat. No. 4,731,957 to Weisinger and U.S. Pat. No. 562,223 to Hausse disclose knife sharpeners using triangular blades which are also adapted to be rotated for exposing fresh sharpening surfaces. However, and as discussed above, these blades do not exhibit rounded corners for the streamlined sharpening effect which is the purpose of this invention.